Thermostatic switch



Oct. 31, 1950 J. H. BRUHN ErAL lrmmos'xwrrc swrrcu Filed lay 28, 1948Patented Oct. 3l, 1950 UNITED THERMOSTATIC SWITCH John H. Bruhn, DesMoines, Iowa, and Leonard W. Bruhn, Kansas City, M0.

Application May 28, 1948, Serial No. 29,864

4 Claims.

This invention relates to thermostats and an object thereof is toprovide a two action thermostat.

Another object of the invention is to provide a double duty thermostat.

A still further object of our invention is to provide a thermostat foroperating both visible and audible alarm systems.

A further object of this invention is to provide -a thermostat soconstructed that it will operate rst one and then another alarm system.

Another object of the invention is to pro-vide a thermostat toalternately operate a plurality of alarm systems.

Another object of this invention is to provide a thermostat havingadjustable means whereby it may either open or close electric alarmsystems at predetermined atmospheric temperatures.

A still further object of our invention is to provide a thermostatformed of a bimetallic bar each end of which is adapted to control anindependent electric system.

Still another object of the invention is to provide a thermostat formedof a bimetallic alloy metal bar having a long and a short arm eachadapted to actuate at different degrees of temperature to open or closeindependent electric circuits.

With the above and such other objects in view as may hereinafter morefully appear, we have invented the thermostat illustrated in theaccompanying drawings in which:

Figure l is a sectional elevational view of our thermostat,

Figure 2 is a longitudinal sectional view of the thermostat shownremoved from its casing,

Figure 3 is a bottom plan view thereof,

Figure 4 is an enlarged detail view of an indica tor.

Figure 5 is an end view showing high and low contact.

In the following specification as well as in the accompanying drawingslike reference characters indicate like parts throughout and in which I0refers to our thermostat as an entirety and I I indicates anon-conductor base. Attached to the up per surface I2 of this base is abimetallic bar I3,

vwhich is bent down intermediate its ends to form a seat Il which issecured to the upper surface I 2 of base IIv by bolts I6 and I6'. Saidseat III is formed nearer the short arm II than the long arm I8 of barI3 for a purpose presently to be explained.

A contact screw I9 is threaded through one end 20 of the base II and itspoint 2| seats directly beneath the extreme free end 22 of arm` I9.Mounted on the screw I9 is a conductor 23 and a lock nut 24, and securedto the under surface of the base I I ls the arm 25 by means of saidconductor or otherwise. The arm 25 terminates in an indice pointer 26which is turned up to the under surface 21 of the enlarged head 28 ofsaid screw I9 and which surface is provided with indicia to indicatevarious temperatures at which the screw I9 may he set to either attract(or repel, as the case may be) the said terminal 22 of arm I8.

Mounted directly under the terminal 29 of the short arm I'I of member I3is a conductor screw 30 on which is mounted a conductor 3|, a lock nut32, an indice 33 and indicia head 3l, similar in all respects to thearrangement of screw I9.

Fixed to the base II adjacent its end 20, is c bracket 35 the upper end36 of which is bent at right angles to extend over and above the saidterminal 22 of arm I8. Threaded through sar end 36 is a conductor screw3l having an indici:L head 38 and a contact point 39 which may beadjusted to contact (or leave) the arm I8 at a predeterminedtemperature.

The base II is mounted within a housing 40 which may be of any suitablematerial such as tin or lava, and it is provided with a series ofapertures 4I above the base, and apertures 42 below the base, which baseis provided with bores I3, whereby a free circulation of atmospheric airmay be constantly in the housing.

The above described thermostat has been designed primarily for acombination of audible and visible fire alarm systems and rst gives analarm in the building Where located due to the more flexible action ofthe long arm I8. The shorter arm IT being more rigid requires greaterheat to actuate it and this arm is connected up with a general alarmsystem connected with a re house or other central point. Therefore if afire is not extinguished after the first alarm the heat raises andactuates the second system.

The device is also adapted to operate signals at predetermined lowtemperatures as for use in orchards, cold storage plants, etc. In thislatter case the screw 31 is connected with the circuit which preferablyoperates on an open circuit for activating signals when a predeterminedlow tempcrature is reached.

Having now described our invention that which we claimy as new anddesire to procure by Letters Patent is:

l. In an alarm thermostat having a base, circuit conducting means and abimetallic thermoasoman static bar, a plurality of contact armscomprising said bar, each oi said arms being of diiierent lengths andhaving one extremity amxed to said base then extending upwardly to forman acute angle with said base and then outwardly in a planesubstantially parallel to said base to form an obtuse angle with saidupwardly extending portion.

2. An alarm thermostat comprising a bimetallic thermostatic bar having aplurality of contact arms of diiierent lengths, points at which saidarms make contact with a circuit conducting means and control indicia toregulate the exact temperature at which said contact as between saidarms and points is to be made, the contact arms of said bi-metallic barhaving one extremity afiixed to said base and then extending upwardly toform an acute angle with said base and then outwardly in a planesubstantially parallel to said base to form an obtuse angle with saidupwardly extending portion.

3. An alarm thermostat comprising a bimetallic thermostatic bar having aplurality o! contact arms of diierent lengths, points at which said armsmake circuit contact, a plurality of -said points being positioned belowsaid bar and one of said points being positioned above said bar, andcontrol indicia to regulate the exact temperature' at which said contactas between said arms and points is to be made, the said contact arms ofsaid bi-metallic par having one extremity afilxed to said base and thenextending upwardly to form an acute angle with said base and' then fcuitconducting means and a bimetallic thermostatic bar having a plurality ofcontact arms, a plurality of circuit contact points positioned belowsaid arms, one circuit contact point positioned above one oi said arms,and control indicia to reilulate the exact temperature at which saidcontact, as between said arms and said points, is to be made,- the saidcontact arms ot said bi-metallic bar having one extremity aiiixed tosaid base and then extending upwardly to form an acute angle with saidbase and then outwardly in a plane substantially parallel to said baseto form an obtuse angle with said upwardly extending portion.

JOHN H. BRUHN.- LEONARD W. BRUHN.

REFERENCES CITED The following references are of record in the ille oithis patent:

UNITED STATES PATENTS

